1. Field
One or more embodiments of the present invention relate to organic light-emitting devices.
2. Description of the Related Art
Organic light-emitting devices (OLEDs) are self-emitting devices that have advantages such as wide viewing angles, excellent (e.g. high) contrast, quick response time, and excellent (e.g. high) brightness, good driving voltage and response speed characteristics, and can provide multicolored images.
A typical OLED has a structure including a first electrode, a hole transport region, an emission layer (EML), an electron transport region, and a second electrode that are sequentially stacked on a substrate. Holes injected from the first electrode move to the EML via the hole transport region, and electrons injected from the second electrode move to the EML via the electron transport region. Carriers (i.e. the holes and the electrons) recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted.